Characterization and strength prediction of promoters regulated by YgiV transcriptional factor of Salmonella enterica serovar Typhimurium

Abstract

Salmonella enterica serovar Typhimurium is a worldwide pathogen, causing several deaths yearly. Host-pathogen interactions are mediated by chemical signaling, which comprises sensing stimuli from both host and its microbiota by the bacterial pathogen. QseBC is a two-component system playing a role in pathogenesis activation through chemical signaling. Assessing the transcriptome of S. Typhimurium ”qseC mutant, it was identified and characterized visP, which encodes a periplasmic protein highly related with virulence, stress response and O-antigen chains biosynthesis. The visP gene is located in an operon which also presents ygiV, encoding a putative AraC/XylS transcriptional regulator. We previously performed an RNA-seq experiment to compare the expression level of genes between S. Typhimurium wild-type and the ”ygiV knockout mutant, and found that YgiV affects genes involved in the pathogenic process of epithelial cells invasion and also alternative carbon sources metabolism. Nonetheless, it could not be asserted which genes are directly regulated by YgiV via binding to cis-regulatory DNA element. To elucidate the mechanism of YgiV-mediated regulation, we propose to perform a Chromatin Immunoprecipitation sequencing (ChIP-seq) experiment to identify the direct targets of YgiV and to characterize the sequence signature of YgiV binding sites and its effect on regulating the transcription level of the gene. Furthermore, we intend to assess the promoter strength of the main targets in RNAseq and ChIP-seq high-throughput experiments through GFP reporter assay, evaluating the transcriptional remodeling displayed by YgiV in S. Typhimurium. These results will provide a deep characterization of YgiV transcriptional regulator, as well as information of how it affects S. Typhimurium transcriptome and may act on pathogenic processes.